Lean Fraction Research Articles

Assessing Fatty Infiltration of Paraspinal Muscles in Patients With Lumbar Spinal Stenosis: Goutallier Classification and Quantitative MRI Measurements.

Objective: Fatty infiltration of paraspinal muscle is associated with spinal disorders. It can be assessed qualitatively (i.e., Goutallier classification) and quantitatively using image processing software. The aims of this study were to compare paraspinal muscle fatty infiltration as assessed using the Goutallier classification vs. quantitative magnetic resonance images (MRI) measurements and to investigate the association between anthropometric parameters and paraspinal muscle morphology and fatty infiltration in patients with symptomatic lumbar spinal stenosis (LSS).Methods: Patients affected by symptomatic LSS scheduled for surgery with available MRI of the lumbar spine were included in this retrospective cross-sectional study. Fatty infiltration at each lumbar level was rated qualitatively according to the Goutallier classification and quantified based on the cross-sectional area (CSA) of the paraspinal muscle, of its lean fraction (LeanCSA), and the ratio between LeanCSA and CSA and the CSA relative to the CSA of vertebral body (RCSA). Considering the muscle as a single unit, overall fatty infiltration according to Goutallier, overall CSA, LeanCSA, LeanCSA/CSA, and RCSA were computed as averages (aGoutallier, aCSA, aLeanCSA, aLeanCSA/aCSA, and aRCSA). Associations among parameters were assessed using Spearman's respective Pearson's correlation coefficients.Results: Eighteen patients, with a mean age of 71.3 years, were included. aGoutallier correlated strongly with aLeanCSA and aLeanCSA/aCSA (R = −0.673 and R = −0.754, both P < 0.001). There was a very strong correlation between values of the left and right sides for CSA (R = 0.956, P < 0.001), LeanCSA (R = 0.900, P < 0.001), and LeanCSA/CSA (R = 0.827, P < 0.001) at all levels. Among all anthropometric measurements, paraspinal muscle CSA correlated the most with height (left: R = 0.737, P < 0.001; right: R = 0.700, P < 0.001), while there was a moderate correlation between vertebral body CSA and paraspinal muscle CSA (left: R = 0.448, P < 0.001; right: R = 0.454, P < 0.001). Paraspinal muscle CSA correlated moderately with body mass index (BMI; left: R = 0.423, P < 0.001; right: R = 0.436, P < 0.001), and there was no significant correlation between aLeanCSA or aLeanCSA/CSA and BMI.Conclusions: The Goutallier classification is a reliable yet efficient tool for assessing fatty infiltration of paraspinal muscles in patients with symptomatic LSS. We suggest taking body height as a reference for normalization in future studies assessing paraspinal muscle atrophy and fatty infiltration.

Characterization of specific volatile components in braised pork with different tastes by SPME‐GC/MS and electronic nose

Braised pork is popular for its delicious flavor around the world and its flavor varies greatly with preparations for achieving different tastes. However, it is difficult to discriminate braised pork from various preparations. In this study, we compared the differences in volatile compounds in lean and fat fractions of braised pork with different tastes using electronic nose (E‐nose) and gas chromatography and mass spectrometry with solid‐phase microextraction (SPME‐GC‐MS). E‐nose distinguished volatile flavor in lean fractions well, while it could not separate fat fractions effectively. W2W, W2S, W1W, and W1S sensors were sensitive to volatile compounds in lean meat. GC‐MS results showed that braised pork of different tastes have their own characteristic volatile compounds. Correlation analysis showed that E‐nose sensor signals were significantly correlated with a relative abundance of volatile compounds by GC‐MS. Volatile compounds and E‐nose sensors had a certain correlation with crude composition, fatty acid composition, and sensory attributes. Thus, E‐nose has the ability to distinguish braised pork with different tastes relating to their own characteristic volatile compounds. PRACTICAL APPLICATIONS: The tastes and volatile compounds of braised pork differ with different preparations. Our GC‐MS results showed that there were differences in types and contents of volatile compounds with different tastes of braised pork. E‐nose sensor signals had a certain correlation with the relative abundance of volatile flavor compounds, both of which were correlated with crude composition, fatty acid composition, and sensory attributes. These results will be helpful for the rapid distinction of different tastes of braised pork by E‐nose.

Assessing fatty infiltration of paraspinal muscles in patients with lumbar spinal stenosis: Goutallier classification and quantitative MRI measurements

Objective: Fatty infiltration of paraspinal muscle is associated with spinal disorders. It can be assessed qualitatively (i.e., Goutallier classification) and quantitatively using image processing software. The aims of this study were to compare paraspinal muscle fatty infiltration as assessed using the Goutallier classification vs. quantitative magnetic resonance images (MRI) measurements and to investigate the association between anthropometric parameters and paraspinal muscle morphology and fatty infiltration in patients with symptomatic lumbar spinal stenosis (LSS). Methods: Patients affected by symptomatic LSS scheduled for surgery with available MRI of the lumbar spine were included in this retrospective cross-sectional study. Fatty infiltration at each lumbar level was rated qualitatively according to the Goutallier classification and quantified based on the cross-sectional area (CSA) of the paraspinal muscle, of its lean fraction (LeanCSA), and the ratio between LeanCSA and CSA and the CSA relative to the CSA of vertebral body (RCSA). Considering the muscle as a single unit, overall fatty infiltration according to Goutallier, overall CSA, LeanCSA, LeanCSA/CSA, and RCSA were computed as averages (aGoutallier, aCSA, aLeanCSA, aLeanCSA/aCSA, and aRCSA). Associations among parameters were assessed using Spearman's respective Pearson's correlation coefficients. Results: Eighteen patients, with a mean age of 71.3 years, were included. aGoutallier correlated strongly with aLeanCSA and aLeanCSA/aCSA (R = -0.673 and R = -0.754, both P < 0.001). There was a very strong correlation between values of the left and right sides for CSA (R = 0.956, P < 0.001), LeanCSA (R = 0.900, P < 0.001), and LeanCSA/CSA (R = 0.827, P < 0.001) at all levels. Among all anthropometric measurements, paraspinal muscle CSA correlated the most with height (left: R = 0.737, P < 0.001; right: R = 0.700, P < 0.001), while there was a moderate correlation between vertebral body CSA and paraspinal muscle CSA (left: R = 0.448, P < 0.001; right: R = 0.454, P < 0.001). Paraspinal muscle CSA correlated moderately with body mass index (BMI; left: R = 0.423, P < 0.001; right: R = 0.436, P < 0.001), and there was no significant correlation between aLeanCSA or aLeanCSA/CSA and BMI. Conclusions: The Goutallier classification is a reliable yet efficient tool for assessing fatty infiltration of paraspinal muscles in patients with symptomatic LSS. We suggest taking body height as a reference for normalization in future studies assessing paraspinal muscle atrophy and fatty infiltration.

Simulation of the Self-Ignition of a Cold Premixed Ethylene-Air Jet in Hot Vitiated Crossflow

The aim of this paper is to analyze the self-ignition of a jet flame in hot vitiated cross flow using Large Eddy Simulation with analytically reduced chemistry. A rich premixed ethylene-air mixture (phi = 1.2) at 300 K is injected into a hot vitiated crossflow at 1500 K. The simulated reacting flow steady-state was validated against experiments in previous publications and the focus of the present work is the transient self-ignition of the jet. It is shown that spontaneous ignition occurs at very lean mixture fractions in the form of reacting patches in the windward jet mixing layer. These patches grow, laterally wrap the jet and extend into the recirculation region. Chemical explosive mode analysis is performed to identify the chemically active regions that are precursors of the patches undergoing spontaneous ignition. It is shown that the self-ignition occurs at very lean fuel concentrations regions, which are leaner and hotter than the most reactive mixture fraction of the jet and crossflow. This is explained by the fact that the scalar dissipation is significantly lower in these very lean regions. Ultimately, the peak heat release moves toward the richer regions and an autoignition cascade governs the steady state flame anchoring.

Dense breast tissue in postmenopausal women is associated with a pro-inflammatory microenvironment in vivo

ABSTRACTInflammation is one of the hallmarks of carcinogenesis. High mammographic density has been associated with increased risk of breast cancer but the mechanisms behind are poorly understood. We evaluated whether breasts with different mammographic densities exhibited differences in the inflammatory microenvironment.Postmenopausal women attending the mammography-screening program were assessed having extreme dense, n = 20, or entirely fatty breasts (nondense), n = 19, on their regular mammograms. Thereafter, the women were invited for magnetic resonance imaging (MRI), microdialysis for the collection of extracellular molecules in situ and a core tissue biopsy for research purposes. On the MRI, lean tissue fraction (LTF) was calculated for a continuous measurement of breast density. LTF confirmed the selection from the mammograms and gave a continuous measurement of breast density. Microdialysis revealed significantly increased extracellular in vivo levels of IL-6, IL-8, vascular endothelial growth factor, and CCL5 in dense breast tissue as compared with nondense breasts. Moreover, the ratio IL-1Ra/IL-1β was decreased in dense breasts. No differences were found in levels of IL-1β, IL-1Ra, CCL2, leptin, adiponectin, or leptin:adiponectin ratio between the two breast tissue types. Significant positive correlations between LTF and the pro-inflammatory cytokines as well as between the cytokines were detected. Stainings of the core biopsies exhibited increased levels of immune cells in dense breast tissue.Our data show that dense breast tissue in postmenopausal women is associated with a pro-inflammatory microenvironment and, if confirmed in a larger cohort, suggests novel targets for prevention therapies for women with dense breast tissue.

A Mass Balance Approach to Identify and Compare Differential Routing of13C-Labeled Carbohydrates, Lipids, and Proteins In Vivo

All animals route assimilated nutrients to their tissues where they are used to support growth or are oxidized for energy. These nutrients are probably not allocated homogeneously among the various tissue and are more likely to be preferentially routed toward some tissues and away from others. Here we introduce an approach that allows researchers to identify and compare nutrient routing among different organs and tissues. We tested this approach by examining nutrient routing in birds. House sparrows Passer domesticus were fed a meal supplemented with one of seven (13)C-labeled metabolic tracers representing three major classes of macronutrients, namely, carbohydrates, amino acids, and fatty acids. While these birds became postabsorptive (2 h after feeding), we quantified the isotopic enrichment of the lean and lipid fractions of several organs and tissues. We then compared the actual (13)C enrichment of various tissue fractions with the predictions of our model to identify instances where nutrients were differentially routed and found that different classes of macronutrients are uniquely routed throughout the body. Recently ingested amino acids were preferentially routed to the lean fraction of the liver, whereas exogenous carbohydrates were routed to the brain and the lipid fraction of the liver. Fatty acids were definitively routed to the heart and the liver, although high levels of palmitic acid were also recovered in the adipose tissue. Tracers belonging to the same class of molecules were not always routed identically, illustrating how this technique is also suited to examine differences in nonoxidative fates of closely related molecules. Overall, this general approach allows researchers to test heretofore unexamined predictions about how animals allocate the nutrients they ingest.

SU‐E‐I‐143: Feasibility of Using Chemical Analysis to Validate Breast Density Measurement from Dual Energy Mammography

Purpose: Currently, there is no accepted standard for measuring breast density. Dual energy mammography, which has demonstrated accurate measurement in phantoms, has been proposed as one possible method. The purpose of this study was to assess the possibility of using chemical analysis to validate measurements of breast density made with a dual energy mammography system.Methods: Fourteen ex‐vivo bovine tissue samples composed of varying amounts of pure lean tissue and pure adipose tissue in increments of 10%, as measured by their lean percentage, were imaged using dual energy mammography. This was followed by chemical analysis of the tissue samples based on desiccation, trituration, and fat extraction with petroleum ether. Breast density, as measured from dual energy mammography, and the glandular volume percentage, as derived from chemical analysis data, were compared to the known lean percentages. Breast density was also compared to the glandular volume percentage.Results: Breast density (BD) was related to the tissue sampleˈs volumetric lean fraction (VLF) by BD = 1.52*VLF + 10.0 (r2&gt;0.99). Glandular volume percentage (GVP) was related to VLF by GVP = 0.74*VLF + 26.1 (r2&gt;0.99). BD was related to GVP by BD= 2.06*GVP‐ 43.59 (r2&gt;0.99) Conclusions: The results of this study show strong linear relationships between different parameters and indicate that chemical analysis should be a useful technique to help validate breast density measurements. The relationship between breast density and glandular volume percentage from a bovine tissue model could help to interpret the analysis of human breast tissue samples of unknown composition.

Transported scalar PDF calculations of autoignition of a hydrogen jet in a heated turbulent co-flow

The joint scalar PDF method, as implemented in FLUENT, was used to simulate the autoignition of a jet of hydrogen in a turbulent co-flow of heated air. While the autoignition phenomenon is intermittent in the experiment, ensemble-averaged data on the effect of the flow on ignition length are available, which enables us to compare them with the steady state calculations.Results of sensitivity tests showed that the choice of chemical mechanism affects the calculation more than the mixing model and model constants. Further calculations for different initial conditions (i.e. temperature and velocity of the jet T jet and U jet and the co-flow T air and U air) have been done using a set of parameters selected after the sensitivity study. Scatter plots and conditional scalar profiles confirmed that the ignition is always initiated in lean mixture fractions. The ignition length was predicted with good accuracy for the case of U jet>U air but not so well for the case of U jet≈U air. For the equal velocity case, increasing the velocity resulted in delayed autoignition time (defined as the ignition length divided by the mean velocity), in agreement with the experimental trend. The results give credence to the use of the joint scalar PDF method for autoignition in non-premixed flows.

The allometric partition of whole body protein in lean fraction of growing pigs using information from three different datasets

The hypothesis that a single allometric relationship relating carcass lean protein (CLP) to whole body protein (WBP) can allow accurate estimates of CLP on pigs of different populations, sex and nutritional history, was tested. Three datasets of different origins were used. Data were representative of 548 pigs, castrated males and females, of 8 pig populations, serially slaughtered over ample empty body weight (EBW) ranges (from 22 to 217 kg). WBP and CLP ranged, respectively, from 2 to 28 and from 1 to 16 kg. The pooled data were run and the following relationship was found: CLP=0.497*WBP1.021 (CV=0.062; rsd=0.501 kg). The residuals were subjected to ANOVA to test the effects due to dataset, pig population within dataset and sex; significant differences between datasets mean residuals (+0.095, SE=0.041; -0.258, SE=0.094; -0.116, SE=0.055 kg, P<0.001) were observed. No differences due to sex and pig populations were found. The average residuals were low and only in few cases they differed from zero. Conclusions: CLP can be accurately predicted from WBP; the coefficients of this function are mainly influenced by the procedures of slaughtering, dissection, sampling and analysis.

Performance of Co-containing NO x storage and reduction catalysts as a function of cycling condition

Co-containing NO x storage and reduction (NSR) catalysts were studied for their NO x storage and NO x conversion behavior. It was found that addition of 5% Co increased the NO x storage capacity of a 1% Rh/15% Ba catalyst by 50% and that of a 1% Pt/15% Ba catalyst by 100%. This promotional effect was attributed to the high oxidizing ability of Co, present in the form of Co 3O 4, providing extra oxidation sites for NO to NO 2 conversion and more contact area for NO 2 spillover to Ba storage sites. Empirical models were developed to predict the NO x conversion capacity of the catalyst as a function of total cycle time and the fraction spent in the lean phase. Using these models, it was found that 5% Co also improved the performance of 1% Pt/15% Ba and 1% Rh/15% Ba catalysts at higher lean fractions, allowing substantial improvement in overall fuel efficiency. The reduction capacity of Co was much less than that of noble metals, such that noble metals were still necessary (although at a reduced loading) for regenerating the catalyst in the rich phase. Along these lines, it was found that a 0.25% Pt/5% Co/15% Ba-containing catalyst showed better performance than a 1% Pt/15% Ba-containing catalyst. This implies that the cost of NSR catalysts can be substantially reduced by replacing some of the Pt with Co as the active oxidizing metal in NSR catalyst formulations.

High-throughput study of the performance of [formula omitted] storage and reduction catalysts as a function of cycling conditions and catalyst composition

NO x storage and reduction (NSR) catalysts were studied both as a function of cyclic operating conditions and Pt, Ba, and Fe weight loadings via high-throughput experimentation using response surface analysis at T = 648 K . An empirical model was developed to predict the catalyst performance as a function of cycle time, lean fraction of cycle time, and catalyst composition. Using this empirical model for a 0.5 wt% Pt/7.5 wt% Ba/2.5 wt% Fe catalyst, it was found that maximum NO x conversion and selectivity to N 2 was obtained for cycle time between 60 and 125 s and a lean fraction < 0.65 . Fe was found to act as a promoter, extending the region of the complete NO x conversion to lower Pt and Ba weight loadings, as well as acting as an oxidizing agent in the absence of Pt and a storage component in the absence of Ba. Finally, it was found that at higher lean fractions, the catalyst performance was governed by the rate at which the stored nitrates were reduced under fuel rich conditions.

Influence of dietary conjugated linoleic acids (CLA) and age at slaughtering on meat quality and intramuscular collagen in rabbits

To assess the effects of dietary conjugated linoleic acids (CLA) on meat composition and intramuscular collagen (IMC), 144 New Zealand White rabbits, half males half females, 55 days old (1.8 kg LW), were assigned to three weight- and sex- balanced groups and given the following dietary supplements: 0.5% sunflower oil, (C); 0.25% sunflower oil plus 0.25% CLA (T1); and 0.5% CLA (T2). The CLA was prepared from sunflower oil and contained 65% CLA isomers, half cis-9, trans-11 and half trans-10, cis-12. Six males and six females from each group (total 36) were slaughtered at 76, 90 and 104 days of age (corresponding to 2.5, 2.8, and 3.1 kg BW, respectively). The lean fraction was higher and the water content significantly higher in the meat of T2 compared to C and T1 for all ages combined. At the third slaughtering (104 days) the meat fat content was significantly lower in group T2. For all ages combined, IMC content, IMC hydroxylysylpyridinoline (HLP) concentration (index of collagen cross-linking) and IMC maturity (HLP/IMC) were significantly lower in the intermediate supplementation group (T1) compared to C and T2, and were also lower in animals slaughtered at 90 days. CLA supplementation has limited effects on the chemical composition of rabbit meat, with positive effects on meat texture and tenderness after supplementation up to 35 days at 0.25%, and a significant decrease in fat content only at high slaughter weight and high supplementation level (0.5%).

Partitioning of protein and lipid deposition in the body of growing pigs

Two amounts of energy intake (12.6 and 16.3 MJ DE/day, respectively) above maintenance requirement were given to entire male pigs from 25 to 105 kg body weight. Slaughter, dissection and chemical analysis in three body fractions on 25, 65 and 105 kg live weight allowed calculation of tissue deposition and tissue partitioning in two weight ranges. On average, 57% of total protein deposition was deposited into the LEAN fraction. Moreover, 68% of total lipid deposition was deposited into the non-lean carcass parts on average. An increase in energy intake resulted in an increase in both lipid and protein deposition. Of this extra protein deposition and extra lipid deposition, 42 and 75% respectively were directed to the non-lean carcass parts in the live weight range 25–65 kg. Above 65 kg live weight, these respective percentages were 71% and 82% on average. Thus, despite the relatively low intake levels, the major part of extra tissue deposition was deposited into non lean carcass tissue. The effect of a 40 kg increase in body weight on protein and lipid deposition rates was small as compared to the effect of an extra 250 g of feed. Thus, for the used feeding regimen, partitioning of protein within the body was mainly effected by nutrition, and not by body weight. It was concluded that a nutrition induced increase in lean tissue deposition rate will be coincided with a substantial increase in body fatness. This is due to an increase in lipid deposition accompanying an increase in protein deposition. Furthermore, an increase in protein deposition enhanced the partitioning of protein to tissues other than lean.

Effect of Cholecystokinin Immunization, Enhanced Food Intake and Growth of Swine on Lean Yield and Carcass Composition

It was previously reported that cholecystokinin (CCK) immunization of swine increased food intake 8.2% and rate of growth 10.6%. This report compares carcass yields of lean, fat and bone tissues of CCK-immunized vs. human serum globulin (hSG) control animals. The experiment involved 24 castrated pigs, age 75 d, weight 25.6 kg, randomly assigned to the CCK-immunized or hSG control groups (2 pigs/pen, 6 pens/group). Food was offered for ad libitum access. Carcasses of CCK-immunized animals (vs. hSG controls) were 8.7% heavier (P less than 0.01) and 2.4% longer (P less than 0.01). Carcass yield and composition were analyzed by dissection to lean, fat and bone fractions and by proximate analysis of the resultant lean fraction. Carcasses from the CCK-immunized animals had 2.7 kg more lean (P = 0.09) and 1.8 kg more fat (P = 0.04). Proximate analysis indicated there were no significant differences in composition of the lean fraction. The 7.2% heavier lean fractions of the CCK-immunized animals contained 9.2% more protein (P = 0.09) and 5.1% more fat (P = 0.05). Lean:fat and protein:fat ratios were not significantly altered.

Magnetic Separation as a Plutonium Residue Enrichment Process

Abstract We have subjected several plutonium contaminated residues to Open Gradient Magnetic Separation (OGMS) on an experimental scale. OGMS experiments on graphite and bomb reduction residues resulted in aplutonium rich fraction and a plutonium lean fraction. Values for the bulk quantity rejected to the lean fraction varied between about 20% to 85% of the feed bulk. The plutonium content of the lean fraction can be reduced from about 2% in the feed to the 0.1% to 0.5% range dependent on the portion of the feed rejected to this lean fraction. These values are low enough in plutonium to meet economic discard limits and be considered for direct discard. Magnetic separation of pyrochemical salts gave less favorable results. While a fraction very rich in plutonium could be obtained, the lean fraction plutonium content was too high for direct discard. This may still have chemical processing applications. OGMS experiments at low magnetic field strength on incinerator ash did give two fractions but the plutonium content of each fraction was essentially identical. Thus, no chemical processing advantage was identified for magnetic separation of this residue.

Composition of lean tissue in healthy volunteers for nutritional studies in health and disease

Measurements of body composition were carried out on 56 healthy female volunteers 20–80 years of age. Anthropometric measurements were made to estimate lean body mass (ANLBM). Total body potassium (K) was measured from the naturally occuring 40K; body nitrogen (N) and calcium (Ca) were measured by neutron activation techniques. Body K, N and Ca reflect intracellular water, protein and bone mineral mass respectively. The 23 older women (mean (±SD) age=62.3±8.5) showed no significant differences from the 33 young adults (mean age 35.2±3.8) with respect to height, total body mass, ANLBM and intracellular water (K) but the older group had significantly less protein (by 17%) and less bone mineral (16%) than younger adults. When normalized for body size, based on height, ANLBM was significantly correlated to intracellular water (r=0.52) and to bone mineral (r=0.39) but correlated to either ANLBM (r=0.05) or to intracellular water (r=0.10). Protein was correlated to bone mineral (r=0.39). Simple anthropometric measurements may provide reasonable estimates of the fat and lean fractions of total body mass. However the composition of lean tissue varies with aging. To determine the essential components of lean tissue, direct measurements of protein and bone mass are required.

A dual beam study with isotopic X- and gamma-rays for in vivo lymph pool assay

Dual beam absorptiometry utilizes differential absorption of X- and gamma rays of differing energy to determine an absorber's component ratio. This principle has been applied to diverse physical and biological problems. Our method, using the 22 and 88 keV emissions from 109Cd, resolves the lean and non-lean mammalian tissue fractions. Accuracy of 1%, and reproducibility of 1–2% is attainable in in vitro measurements. Techniques have been developed to apply this system to the more complicated applications involved in human studies. A scanning device capable of measuring limbs has been developed. Mathematical treatment provides an integrated value of lean fraction over the scanned area. Lymphedema is a painful malady in which blockage of lymph flow causes swelling and distension of the extremities. Compressive therapy is the preferred medical treatment. There has been no accurate quantitative index of the efficacy of this therapy. Our research program uses dual beam analysis as a unique quantitative measure of the lymph transport. Lymph pool change is equated to change in the lean. Five measurements are made on subjects undergoing a two week regimen of compressive therapy. These absorptiometric results are analyzed for correlation to other indices of treatment effect. Data shows a progressive decrease in the lean tissue component over the treatment period. Changes seen vary with the individual and the severity of involvement. This study showed that the largest transport rate occurs in the first treatment days. Absorptiometry accurately monitors total adipose mass, total non-adipose mass, extremely cross section, and change in lymph pooling.

Aspects of the Bioenergetics of Great Basin Lizards

Late summer densities of leopard lizards (Crotaphytus wislizeni), western whiptails (Cnemidophorus tigris) and side-blotched lizards (Uta stansburiana) inhabiting a shadscale-bud sage community in southern Idaho were estimated by sight census at about 10, 8.5 and 10/ha respectively. Biomass and standing crop estimates for the total lizard population were calculated as 384 g/ha and 636 kcal/ha. These lizards subsisted almost entirely upon insects, particularly grasshoppers, ants and lepidopterous larvae. Caloric content of the food ranged from 4.9 to 5.2 kcal/g. Assimilation efficiency of these lizards living in the wild on natural diets ranged from 78 to 86 per cent. Water, ash and lean fractions of carcasses varied little seasonally. Fat content and live weight caloric density increased prior to torpor.